Flies

Flies belong to the Order Diptera. There are 98 different Australian families & 7786 different species of flies in Australia alone. Mozzies, house flies, bush flies, & blowies all belong to this group.

House Flies

Adults are usually stocky & strongly bristled. There are 180 species in this family & two of the most familiar are the Musca domestica, the cosmopolitan house fly & Musca vetustissima, the bush fly. Both are a great nuisance.

Life cycle

Within a week of reaching adulthood, a female adult fly lays batches of about 100 eggs in material suitable for larval feeding. Warm, moist, organic materials are preferred. The tapered, maggot-shaped larvae may hatch within a day. Larvae molt about 4 times during feeding, which may last up to a week or even less in more favorable conditions. Once fed, the larvae usually crawl away from the moist food to find a drier location in which to pupate. The pupae remain immobile for up to a week, at which time the adult emerges. The life cycle of the house fly is usually 2 – 4 weeks but in summer when conditions are favorable up to 12 generations may be produced. Over winter flies will become inactive, hidden & protected, or as larvae that develop very slowly.

The house fly is probably the most annoying insect pest indoors and is found in most parts of Australia. Typically the house fly alternates between materials that are likely to harbor disease causing organisms (e.g. animal excrement) and human foods, utensils & food preparation surfaces. They are known to transmit important diseases such as typhoid & the abundance of house flies in an area is sometimes used to indicate the efficiency of waste disposal & general sanitary standards of that region.

The bush fly is possibly the most widely known & annoying flying pest in the outdoors during Australian summers & is attributable to much of the use of personal insect repellant products during this time. The appearance of this fly is similar to the house fly, except it is smaller & the lifecycle is also similar & usually takes about 2 – 5 weeks to complete. The adults seek large animals, including humans, & remain on & around them for hours at a time, being attracted to sweat, tears, saliva & in the case of grazing animals, faeces. They are known to play an active role in the transmission of certain eye infections to humans & livestock & may also serve in the transmission of enteric diseases of humans.

Some species of flies are predators as adults, & some, like the stable fly, Stomoxys calcitrans, are blood sucking. The stable fly is usually found around dairies & other intensive farming facilities & biting & annoyance of livestock can reduce yields. The larvae of all these flies live in many different habitats, with dead and putrefying flesh, fungi, & rotting vegetation being the most important.

Blow Flies

There are 140 species of these small to medium sized flies. Many are metallic green or blue, others are mixtures of brown & black. The larvae of most of these species develop in dead & putrefying flesh or dung, although there are species that are parasitic. Blow flies will usually lay their eggs in dead & putrefying flesh where the larvae will feed not only on the rotten flesh but on the other larvae. Yuck! While many blowflies are beneficial by speeding up decomposition of carcasses, there are some economically important species which attack living animals. The best known is the introduced Lucilia cuprina which causes ‘blowfly-strike’ in sheep when the larvae start feeding on inflamed skin under the wool, & spread into the flesh.

Life cycle

Within a week of reaching adulthood, a female adult fly lays batches of about 100 eggs in material suitable for larval feeding. Warm, moist, organic materials are preferred. The tapered, maggot-shaped larvae may hatch within a day. Larvae molt about 4 times during feeding, which may last up to a week or even less in more favorable conditions. Once fed, the larvae usually crawl away from the moist food to find a drier location in which to pupate. The pupae remain immobile for up to a week, at which time the adult emerges. The life cycle of the house fly is usually 2 – 4 weeks but in summer when conditions are favorable up to 12 generations may be produced. Over winter flies will become inactive, hidden & protected, or as larvae that develop very slowly.

The house fly is probably the most annoying insect pest indoors and is found in most parts of Australia. Typically the house fly alternates between materials that are likely to harbor disease causing organisms (e.g. animal excrement) and human foods, utensils & food preparation surfaces. They are known to transmit important diseases such as typhoid & the abundance of house flies in an area is sometimes used to indicate the efficiency of waste disposal & general sanitary standards of that region.

The bush fly is possibly the most widely known & annoying flying pest in the outdoors during Australian summers & is attributable to much of the use of personal insect repellant products during this time. The appearance of this fly is similar to the house fly, except it is smaller & the lifecycle is also similar & usually takes about 2 – 5 weeks to complete. The adults seek large animals, including humans, & remain on & around them for hours at a time, being attracted to sweat, tears, saliva & in the case of grazing animals, faeces. They are known to play an active role in the transmission of certain eye infections to humans & livestock & may also serve in the transmission of enteric diseases of humans.

Some species of flies are predators as adults, & some, like the stable fly, Stomoxys calcitrans, are blood sucking. The stable fly is usually found around dairies & other intensive farming facilities & biting & annoyance of livestock can reduce yields. The larvae of all these flies live in many different habitats, with dead and putrefying flesh, fungi, & rotting vegetation being the most important.